Influence of timolol, benzalkonium-preserved timolol, and benzalkonium-preserved brimonidine on oxidative stress biomarkers in the tear film.

PURPOSE: The objective of this study was to investigate the influence of topical preservative-free timolol, benzalkonium chloride(BAC)-preserved timolol, BAC-preserved timolol, and BAC-preserved brimonidine on total protein concentration, advanced oxidation protein products (AOPP) content, total sulfhydryl groups content, the activity of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), as well as Total Oxidant Status (TOS), Total Antioxidant Response, and Oxidative Stress Index (OSI) in the tear film. METHODS: The patients were divided into four groups: group C (n = 25)-control group-subjects who did not use topical antiglaucoma medications, group T (n = 17)-patients using topical preservative-free timolol, group T + BAC (n = 24)-patients using topical BAC-preserved timolol, and group BR + BAC (n = 19)-patients using topical BAC-preserved brimonidine. RESULTS: The SOD, CAT, and GPx activities as well as AOPP, TOS, and OSI were found to be higher in the tear film of patients treated with BAC-preserved topical timolol or brimonidine in comparison with patients treated with preservative-free timolol or patients who did not use antiglaucoma topical medications. CONCLUSIONS: This indicates that using BAC-preserved topical medications increases oxidative stress in the tear film and may, in the long-term, contribute to the clinical presentation of dry eye disease.

Effect of Berberine on Glycation, Aldose Reductase Activity, and Oxidative Stress in the Lenses of Streptozotocin-Induced Diabetic Rats In Vivo-A Preliminary Study.

Diabetes mellitus affects the eye lens, leading to cataract formation by glycation, osmotic stress, and oxidative stress. Berberine, an isoquinoline alkaloid, is a natural compound that has been reported to counteract all these pathological processes in various tissues and organs. The goal of this study was to evaluate whether berberine administered at a dose of 50 mg/kg by oral gavage for 28 days to rats with streptozotocin-induced diabetes reveals such effects on the biochemical parameters in the lenses. For this purpose, the following lenticular parameters were studied: concentrations of soluble protein, non-protein sulfhydryl groups (NPSH), advanced oxidation protein products (AOPP), advanced glycation end-products (AGEs), thiobarbituric acid reactive substances (TBARS), and activities of aldose reductase (AR), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx). Diabetes induced unfavorable changes in the majority of the examined parameters. The administration of berberine resulted in an increased soluble protein level, decreased activity of AR, and lowered AOPP and AGEs levels. The results suggest that berberine administered orally positively affects the lenses of diabetic rats, and should be further examined with regard to its anticataract potential.

Chrysin Reduces Oxidative Stress but Does Not Affect Polyol Pathway in the Lenses of Type 1 Diabetic Rats.

Prolonged hyperglycemia is one of the main causes of reactive oxygen species and free radicals generation in diabetes which may affect various organs, including the eye. Oxidative damage to proteins and lipids in the eye lens could lead to cataract formation. To cope with oxidative stress, the endogenous antioxidative system may be supported by the supplementation of exogenous antioxidants. The aim of this study was to evaluate the effect of chrysin, a natural flavonoid, on oxidative stress and polyol pathway-related markers in the lenses of streptozotocin-induced type 1 male diabetic rats. Chrysin at doses of 50 and 100 mg/kg was administered by gavage for 28 days. This treatment resulted in a decrease in antioxidative enzymes activity and oxidative stress index. Moreover, chrysin administration elevated the reduced glutathione level in the lenses. A decrease in the markers linked to oxidative damage to proteins and lipids in the lenses was noted, especially after treatment with 50 mg/kg of chrysin. Neither of the chrysin doses affected glycemia-related markers in the serum or altered parameters related to the polyol pathway and advanced glycation end-products level in the lenses of diabetic rats. Upon obtaining results, it can be concluded that chrysin reveals antioxidative activity in the lenses but shows no antihyperglycemic or antiglycation properties.

Effect of Rosmarinic Acid and Sinapic Acid on Oxidative Stress Parameters in the Cardiac Tissue and Serum of Type 2 Diabetic Female Rats.

Cardiovascular diseases are one of the most common complications of type 2 diabetes. They are considered the leading cause of death among diabetics. One of the mechanisms underlying diabetic cardiovascular complications is oxidative stress. Many phenolic acids are regarded as antioxidants. The aim of the study was to investigate the effect of rosmarinic acid (RA) and sinapic acid (SA) on oxidative stress parameters in the cardiac tissue and serum of type 2 diabetic female rats. Additionally, the effect of these compounds on glucose homeostasis and lipid profile in the serum was evaluated. Type 2 diabetes was induced with high-fat diet and streptozotocin. RA at the doses of 10 and 50 mg/kg and SA at the doses of 5 and 25 mg/kg were administrated orally for 28 days. Untreated diabetic rats exhibited unfavorable changes in glucose metabolism and lipid profile. Changes in the enzymatic and non-enzymatic markers indicated the onset of oxidative stress in these animals. The results showed that the higher doses of the tested phenolic acids-50 mg/kg of RA and 25 mg/kg of SA-revealed beneficial effects on oxidative stress in the cardiac tissue of diabetic rats.

Effect of Topical Prostaglandin F2α Analogs on Selected Oxidative Stress Parameters in the Tear Film.

Background and Objectives: Topically administered antiglaucoma medications, especially those containing benzalkonium chloride (BAC), may cause local adverse effects and compromise ocular surface. The aim of the study was to assess the effect of topical prostaglandin F2α analogs (PGAs): preservative-free latanoprost, BAC-preserved latanoprost, preservative-free tafluprost, and BAC-preserved bimatoprost, on selected oxidative stress parameters in the tear film. Materials and Methods: The patients were divided into five groups: group C (n = 25) control group-subjects who did not use topical antiglaucoma medications, group L (n = 22)-patients using topical preservative-free latanoprost, group L+BAC (n = 25)-patients using topical BAC-preserved latanoprost, group T (n = 19)-patients using topical preservative-free tafluprost, and group B+BAC (n = 17)-patients using topical BAC-preserved bimatoprost. The oxidative stress markers in the tear film samples were evaluated: total protein (TP) concentration, advanced oxidation protein products (AOPP) content, total sulfhydryl (-SH) groups content, the activity of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), as well as Total Oxidant Status (TOS), Total Antioxidant Response (TAR), and Oxidative Stress Index (OSI). Results: The TP concentrations in the groups L, L+BAC, and B+BAC were statistically significantly higher in comparison with group C. The SOD and CAT activities in the groups L+BAC and B+BAC were statistically significantly higher when compared to group C. As compared to group C, AOPP and TOS were statistically significantly higher in all the study groups. OSI was found to be statistically significantly higher in the groups L+BAC, T, and B+BAC in comparison with group C. Conclusion: Use of topical PGAs by the patients with ocular hypertension or primary open-angle glaucoma is associated with increased oxidative stress in the tear film which is additionally exacerbated by the presence of BAC in the formulation.

Effect of caffeine on biomarkers of oxidative stress in lenses of rats with streptozotocin-induced diabetes.

INTRODUCTION: One of the major causes of cataract in diabetes is oxidative stress induced by reactive oxygen species (ROS). Nowadays, new substances with antioxidative properties that may prevent cataract development are needed. One such substance is caffeine - an alkaloid with well-documented antioxidative activity. MATERIAL AND METHODS: The study was conducted on lenses obtained from female rats, divided into 3 groups: control rats; diabetic rats; diabetic rats treated with caffeine at a dose of 20 mg/kg p.o. Type 1 diabetes was induced by streptozotocin (60 mg/kg i.p.). After 4 weeks of caffeine administration, the rats were sacrificed, and the lenses were collected, weighed and homogenized in PBS. The homogenate was used for analysis of protein content, glutathione (GSH) concentration, advanced oxidation protein product (AOPP) concentration, malondialdehyde (MDA) concentration and the activity of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx). RESULTS: The SOD, CAT and GPx activities were found to be higher in the lenses of diabetic rats. There were also increased MDA and AOPP concentrations as well as decreased GSH concentration. The administration of caffeine resulted in decreased activity of SOD, CAT and GPx. The treatment with caffeine also caused an increase of GSH concentration and a decrease of MDA and AOPP concentrations. CONCLUSIONS: The results of the present study may be of relevance in determining the effect of caffeine on the processes induced by ROS in vivo. Further, they can be an indication for clinical observations aiming at the assessment of both preventive and therapeutic effects of caffeine in cataract.

Rosmarinic and Sinapic Acids May Increase the Content of Reduced Glutathione in the Lenses of Estrogen-Deficient Rats.

Oxidative stress is believed to be associated with both postmenopausal disorders and cataract development. Previously, we have demonstrated that rosmarinic and sinapic acids, which are diet-derived antioxidative phenolic acids, counteracted some disorders induced by estrogen deficiency. Other studies have shown that some phenolic acids may reduce cataract development in various animal models. However, there is no data on the effect of phenolic acids on oxidative stress markers in the lenses of estrogen-deficient rats. The study aimed to investigate whether administration of rosmarinic acid and sinapic acid affects the antioxidative abilities and oxidative damage parameters in the lenses of estrogen-deficient rats. The study was conducted on three-month-old female Wistar rats. The ovariectomized rats were orally treated with rosmarinic acid at doses of 10 and 50 mg/kg or sinapic acid at doses of 5 and 25 mg/kg, for 4 weeks. The content of reduced glutathione (GSH), oxidized glutathione and amyloid ß1-42, as well as products of protein and lipid oxidation, were assessed. Moreover, the activities of superoxide dismutase, catalase, and some glutathione-related enzymes in the lenses were determined. Rosmarinic and sinapic acids in both doses resulted in an increase in the GSH content and glutathione reductase activity. They also improved parameters connected with protein oxidation. Since GSH plays an important role in maintaining the lens transparency, the increase in GSH content in lenses after the use of rosmarinic and sinapic acids seems to be beneficial. Therefore, both the investigated dietary compounds may be helpful in preventing cataract.

Effect of Rosmarinic Acid on the Serum Parameters of Glucose and Lipid Metabolism and Oxidative Stress in Estrogen-Deficient Rats.

Rosmarinic acid is found in medicinal and spice plants such as rosemary, lemon balm, and mint. The aim of the study was to investigate the effect of rosmarinic acid on parameters of glucose and lipid metabolism and parameters of oxidative stress in rats in the early phase of estrogen deficiency. The study was carried out on mature female Wistar rats divided into the following groups: sham-operated control rats, ovariectomized control rats, and ovariectomized rats treated orally with rosmarinic acid at a dose of 10 mg/kg or 50 mg/kg daily for 28 days. The concentration of sex hormones, parameters related to glucose and lipid metabolism as well as parameters of antioxidant abilities and oxidative damage were determined in the blood serum. In the ovariectomized control rats, the homeostasis model assessment of insulin resistance (HOMA-IR) index and cholesterol concentration increased, the superoxide dismutase activity increased, and the reduced glutathione concentration decreased. Administration of rosmarinic acid at both doses induced decreases in the fructosamine concentration and HOMA-IR, an increase in the concentration of reduced glutathione, and a decrease in the concentration of advanced oxidation protein products in ovariectomized rats. Moreover, rosmarinic acid at a dose of 50 mg/kg induced a decrease in the total cholesterol and triglyceride concentrations. The results indicate that rosmarinic acid may be useful in the prevention of metabolic disorders associated with estrogen deficiency, however further studies are necessary.

Effect of Resveratrol, a Dietary-Derived Polyphenol, on the Oxidative Stress and Polyol Pathway in the Lens of Rats with Streptozotocin-Induced Diabetes.

Resveratrol is found in grapes, apples, blueberries, mulberries, peanuts, pistachios, plums and red wine. Resveratrol has been shown to possess antioxidative activity and a variety of preventive effects in models of many diseases. The aim of the study was to investigate if this substance may counteract the oxidative stress and polyol pathway in the lens of diabetic rats. The study was conducted on the rats with streptozotocin-induced type 1 diabetes. After the administration of resveratrol (10 and 20 mg/kg po for 4 weeks), the oxidative stress markers in the lens were evaluated: activity of superoxide dismutase, catalase and glutathione peroxidase, as well as levels of total and soluble protein, level of glutathione, vitamin C, calcium, sulfhydryl group, advanced oxidation protein products, malonyldialdehyde, Total Oxidant Status and Total Antioxidant Reactivity. The obtained results indicate that the administration of resveratrol to the diabetic rats shows antioxidative properties. It is not a result of antiglycaemic activity but resveratrol probably directly affects the antioxidative system. Resveratrol did not affect the polyol pathway in the lens of diabetic rats. Our results may indirectly indicate benefits of consumption of foods as well as dietary supplements containing resveratrol in diminishing oxidative stress in lenses of individuals suffering from diabetes mellitus.

Antioxidative effect of flavonoid naringenin in the lenses of type 1 diabetic rats.

Oxidative stress arising during diabetes may lead to cataract formation. Thus, in order to prevent oxidative stress development, antioxidants could be considered helpful agents. Naringenin, a flavonoid with a well-documented antioxidative activity, can be found in many plant-derived products, especially citrus fruits. The aim of the study was to examine the effect of naringenin on oxidative stress markers in the lenses of type 1 diabetic rats. The study was conducted on 3-month-old male Wistar rats with streptozotocin-induced type 1 diabetes. The rats were treated orally with naringenin at the doses of 50 and 100 mg/kg for 4 weeks. In the lenses obtained from the animals, enzymatic and non-enzymatic parameters connected with oxidative stress were measured. The enzymatic parameters included superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and glucose-6-phosphate dehydrogenase activity. For non-enzymatic parameters, the total thiol groups, reduced and oxidized glutathione, protein carbonyl groups, advanced oxidation protein products, malondialdehyde and vitamin C level were assayed. Oral administration of naringenin counteracted most of the unfavorable changes induced by diabetes, including reduction of elevated antioxidative enzymes activity and amelioration of oxidative damage in proteins and lipids. Naringenin administered orally reduces oxidative stress markers in the lenses of type 1 diabetic rats.

The Effects of Sinapic Acid on the Development of Metabolic Disorders Induced by Estrogen Deficiency in Rats.

Sinapic acid is a natural phenolic acid found in fruits, vegetables, and cereals, exerting numerous pharmacological effects. The aim of the study was to investigate the influence of sinapic acid on biochemical parameters related to glucose and lipid metabolism, as well as markers of antioxidant abilities and parameters of oxidative damage in the blood serum in estrogen-deficient rats. The study was performed on 3-month-old female Wistar rats, divided into 5 groups, including sham-operated control rats, ovariectomized control rats, and ovariectomized rats administered orally with estradiol (0.2 mg/kg) or sinapic acid (5 and 25 mg/kg) for 28 days. The levels of estradiol, progesterone, interleukin 18, insulin, glucose, fructosamine, lipids, and enzymatic and nonenzymatic antioxidants (superoxide dismutase, catalase, and glutathione); total antioxidant capacity; and oxidative damage parameters (thiobarbituric acid-reactive substances, protein carbonyl groups, and advanced oxidation protein products) were determined in the serum. Estradiol counteracted the carbohydrate and cholesterol metabolism disorders induced by estrogen deficiency. Sinapic acid increased the serum estradiol concentration; decreased insulin resistance and the triglyceride and total cholesterol concentrations; and favorably affected the parameters of antioxidant abilities (reduced glutathione, superoxide dismutase) and oxidative damage (advanced oxidation protein products).

Diosmin ameliorates the effects of oxidative stress in lenses of streptozotocin-induced type 1 diabetic rats.

BACKGROUND: Diabetic cataractogenesis is a complex process connected with hyperglycemia and oxidative stress. Free radicals induce many unfavorable changes in the activity of the antioxidative enzymes and may also lead to oxidative damage. Since diosmin, a plant-derived flavonoid, reveals antioxidative activity, the aim of the study was to investigate if this substance may counteract the oxidative stress in the lenses of diabetic rats. METHODS: The study was conducted on the male Wistar rats with streptozotocin-induced type 1 diabetes. After the administration of diosmin at the doses of 50 and 100mg/kg for 4 weeks the oxidative stress markers in the lenses of these rats were evaluated. Tested markers included: activity of superoxide dismutase, catalase and glutathione peroxidase, as well as levels of total and soluble protein, level of glutathione, vitamin C, advanced oxidation protein products and malonyldialdehyde. RESULTS: The obtained results indicate that the administration of diosmin to the diabetic rats counteracted the unfavorable changes induced by diabetes in the lenses. CONCLUSION: It can be assumed that diosmin may be a promising compound in prevention or delaying the cataract formation during diabetes.

Glabridin and glycyrrhizic acid show no beneficial effect on the chemical composition and mechanical properties of bones in ovariectomized rats, when administered in moderate dose.

BACKGROUND: One of the major causes of osteoporosis and bone fracture in postmenopausal women is estrogen deficiency. To prevent the fractures, and avoid the side effects of hormone replacement therapy, phytoestrogens including the isoflavonoids are used. In the presented study two constituents occurring in the licorice root-the isoflavane glabridin and triterpenoid saponin glycyrrhizic acid were examined on the skeletal system of ovariectomized rats. METHODS: The female Wistar rats were divided into five groups: control group, ovariectomized group as well as three ovariectomized groups treated with estradiol (0.2mg/kg), glabridin (5mg/kg) or glycyrrhizic acid (15mg/kg). All substances were administered orally for 4 weeks. The estradiol served as a positive control. The mechanical properties of femoral diaphysis, tibial metaphysis and femoral neck were assessed using bending and compression tests. Moreover the chemical composition of the femur, tibia and L-4 vertebra - content of water, organic substances and minerals - was determined. RESULTS: Ovariectomy induced unfavorable changes in the skeletal system of the rats. Administration of glabridin and glycyrrhizic acid to the ovariectomized rats did not improve analyzed parameters of the bones. CONCLUSION: Obtained results indicate, that the tested substances revealed no beneficial effect on the mechanical properties and chemical composition of the tested bones, thus they cannot be used as the osteoporosis protective agents.

EFFECT OF GLABRIDIN AND GLYCYRRHIZIC ACID ON HISTOMORPHOMETRIC PARAMETERS OF BONES IN OVARIECTOMIZED RATS.

Licorice is a medicinal plant showing many therapeutic activities. Its roots contain numerous pharmacologically active compounds such as a triterpenoid saponin--glycyrrhizic acid and an isoflavan--glabridin. There are reports indicating that glabridin exhibits estrogen-like activity, therefore it can be classified into phytoestrogens, which may soothe menopause symptoms including postmenopausal osteoporosis. Due to this fact, the aim of the presented study was to evaluate the effect of glabridin and glycyrrhizic acid on histomorphometric parameters of bones in rats with ovariectomy-induced osteoporosis. The animals were divided into 6 group: (C)--control rats, (OVX)--ovariectomized rats, (OVX + E)--ovariectomized rats receiving estradiol at a dose of 0.1 mg/kg p.o., (OVX + G)--ovariectomized rats receiving genistein at a dose of 5 mg/kg p.o., (OVX + GL --ovariectomized rats treated with glabridin at a dose of 5 mg/kg p.o. and (OVX + GA)--ovariectomized rat administered with glycyrrhizic acid at a dose of 15 mg/kg p.o. Estradiol and genistein served as the positive controls in the study. Several macrometric and histomorphometric parameters were analyzed in the bones of tested rats. Obtained results indicate that glabridin shows slightly positive effect on osteoporotically changed bone tissue, and glycyrrhizic acid reveals meager influence on skeletal system with no preventive significance.

EFFECT OF DIETARY FLAVONOID NARINGENIN ON BONES IN RATS WITH OVARIECTOMY-INDUCED OSTEOPOROSIS.

Naringenin is a dietary flavanone which can be found in many products such as citrus fruits. This substance reveals multiple pharmacological activities such as antiinflammatory and antioxidative. During the menopause, the estrogen deficiency occurs, thus naringenin, which is also considered as a phytoestrogen, may be useful in the treatment of menopause-associated osteoporosis. The aim of the presented study was to examine the effect of naringenin on the mechanical properties, chemical composition and the histomorphological parameters of bones in the rats with ovariectomy-induced osteoporosis. The female Wistar rats were divided into 4 groups: sham-operated, ovariectomized, ovariectoiized treated with estradiol (0.2 mg/kg p.o.) and ovariectomized treated with naringenin (50 mg/kg p.o.), and the tested substances were administered for 4 weeks. The obtained results show that ovariectomy caused the characteristic changes in the skeletal system of rats - there was deterioration in mechanics, chemistry and histomorphometry. The estradiol administered to the rats served as positive control for the experiment. Administration of naringenin to the ovariectomized rats affected neither the bone chemical content nor the mechanical properties, however, there was a slight improvement in the bone microarchitecture in the tissue affected by osteoporosis. It can be concluded that the intake of naringenin in dietary products is not harmful and may even bring beneficial effect on the bones histomorphometry during postmenopausal osteoporosis.

BIOCHANIN A SHOWS NO EFFECT ON SKELETAL SYSTEM IN OVARIECTOMIZED RATS, WHEN ADMINISTERED IN MODERATE DOSE.

Biochanin A is a naturally occurring isoflavone. Its main sources are clover species such as Trifolium pretense, Trifolium subterraneum or Trifolium incarnatum. Phytoestrogens, including isoflavones, are plant-derived substances, which exhibit estrogen-like properties, thus they may be used as an alternative for hormonal replacement therapies and prevent postmenopausal osteoporosis. Therefore, the aim of the presented study, was to investigate the effect of biochanin A on chemistry and mechanical properties of skeletal system in rats with ovariectomy-induced osteoporosis. The animals were divided into 4 groups--(I) sham-operated rats, (II) ovariectomized rats, (III) ovariectomized rats receiving estradiol at a dose of 0.2 mg/kg p.o., which were a positive control, and (IV) ovariectomized rats receiving biochanin A at a dose of 5 mg/kg p.o. for four weeks. The administered dose of biochanin A is considered as moderate for human, which can be received in the dietary supplements, and was established using ten-fold conversion rate resulting from faster metabolism in rats. Obtained results showed that ovariectomy induced harmful changes in bone tissue, causing worsening in both chemistry and mechanical parameters in bones. Administration of biochanin A to ovariectomized rats did not affect any changes in bone tissue in comparison to the bones of untreated ovariectomized rats. There was neither improvement nor deterioration noted in chemical composition and mechanical properties in all analyzed bones. Basing on the results, it could be concluded, that biochanin A administered in a moderate dose shows no influence on bone tissue of rats with ovariectomy-induced osteoporosis.

Effect of formononetin on mechanical properties and chemical composition of bones in rats with ovariectomy-induced osteoporosis.

Formononetin is a naturally occurring isoflavone, which can be found in low concentrations in many dietary products, but the greatest sources of this substance are Astragalus membranaceus, Trifolium pratense, Glycyrrhiza glabra, and Pueraria lobata, which all belong to Fabaceae family. Due to its structural similarity to 17 ß -estradiol, it can mimic estradiol's effect and therefore is considered as a "phytoestrogen." The aim of this study was to examine the effect of formononetin on mechanical properties and chemical composition of bones in rats with ovariectomy-induced osteoporosis. 12-week-old female rats were divided into 4 groups: sham-operated, ovariectomized, ovariectomized treated with estradiol (0.2 mg/kg) and ovariectomized treated with formononetin (10 mg/kg). Analyzed substances were administered orally for 4 weeks. Ovariectomy caused osteoporotic changes, which can be observed in bone biomechanical features (decrease of maximum load and fracture load and increase of displacements for maximum and fracture loads) and bone chemical composition (increase of water and organic fraction content, while a decrease of minerals takes place). Supplementation with formononetin resulted in slightly enhanced bone mechanical properties and bone chemistry improvement (significantly lower water content and insignificantly higher mineral fraction content). To summarize, administration of formononetin to ovariectomized rats shows beneficial effect on bone biomechanical features and chemistry; thus, it can prevent osteoporosis development.

Arabidopsis suppressor mutant of abh1 shows a new face of the already known players: ABH1 (CBP80) and ABI4-in response to ABA and abiotic stresses during seed germination.

Although the importance of abscisic acid (ABA) in plant development and response to abiotic and biotic stresses is well recognized, the molecular basis of the signaling pathway has not been fully elucidated. Mutants in genes related to ABA are widely used as a tool for gaining insight into the mechanisms of ABA signal transduction and ABA-dependent stress response. We used a genetic approach of a suppressor screening in order to decipher the interaction between ABH1 (CBP80) and other components of ABA signaling. ABH1 (CBP80) encodes a large subunit of CBC (CAP BINDING COMPLEX) and the abh1 mutant is drought-tolerant and hypersensitive to ABA during seed germination. The suppressor mutants of abh1 were generated after chemical mutagenesis. The mutant named soa1 (suppressor of abh1 hypersensitivity to ABA 1) displayed an ABA-insensitive phenotype during seed germination. The genetic analysis showed that the soa1 phenotype is dominant in relation to abh1 and segregates as a single locus. Based on soa1's response to a wide spectrum of physiological assays during different stages of development, we used the candidate-genes approach in order to identify a suppressor gene. The molecular analysis revealed that mutation causing the phenotype of soa1 occurred in the ABI4 (ABA insensitive 4) gene. Analysis of pre-miR159 expression, whose processing depends on CBC, as well as targets of miR159: MYB33 and MYB101, which are positive regulators of ABA signaling, revealed a possible link between CBP80 (ABH1) and ABI4 presented here.